January 9, 2014

Antarctic Research Shows SMOS And GOCE Data Similarities

Researchers who braved the harsh conditions of the Antarctic ice sheet will help bring about a better understanding of what lies beneath the South Pole.

Dome-C on the Antarctic Plateau is one of the coldest places on Earth. The region is extremely dry and is essentially a cold-barren white desert. While these conditions are not ideal for a vacation, they do offer a stable place to check the validity of data from the European Space Agency’s SMOS and GOCE Earth observation satellites.

Researchers were sent to this remote region last year to carry out a field campaign for ESA to check out how the space agency’s Earth observation satellites have done. SMOS carries and L-band microwave radiometer that captures images of “brightness temperature” to measure soil moisture and ocean salinity. GOCE mapped out Earth’s gravity for over four years until its mission ended last year.

The team spent two weeks flying over an area of 217 square miles in a Basler-67 research airplane from the Concordia research station at Dome-C . This plane features two sensors to help conduct research, including a radiometer which records surface microwave emissions and a gravity meter. ESA said Dome-C represents an ideal reference point to check the health and stability of the radiometer on board SMOS.

Gravity measurements taken by the team can be used to verify GOCE’s measurements of local gravity gradients. No major airborne gravity surveys have been carried out in this remote area before, so this mission helped to fill in the gap of this research.

The very different measurements taken by the team surprisingly show similar patterns across the Antarctic ice surveyed by the plane, despite using two completely different instruments.

“The major, and I must say unexpected, highlight of the campaign was the remarkable similarity between spatial patterns observed by both the gravity and microwave instruments,” René Forsberg, the gravity expert from the Technical University of Denmark, said in a statement. “It looks like the SMOS L-band signal contains information from much deeper below the surface than had been previously thought.”

ESA’s Tânia Casal said that although the SMOS mission was originally planned to map out soil moisture and ocean salinity, the results from this mission could lead to new scientific discoveries beneath the Antarctic ice surface using SMOS and other gravity missions like GOCE.

“I was surprised to see how much and how quickly the microwave brightness temperatures change when flying across the East Antarctic Plateau. These variations, just a few kilometers apart, have never been measured before,” Niels Skou, from the Technical University Denmark, said in a statement. “These results will play an important role in comparing SMOS measurements to those from NASA’s Aquarius and SMAP missions, which make similar measurements.”